There are a number of devices which move a collet in order to close its jaws. These devices typically include a draw tube to axially draw the collet within a nosepiece, thus causing the collet to close upon a work piece that has been placed within it. A double acting cylinder/piston actuator is typically used, including a check valve for each of the inlets to maintain fluid pressure on the piston. The check valves are typically installed within the cylinder body, which necessarily requires complete disassembly of the device in order to repair or replace these valves.
The draw tube is also typically assembled with the device such that removal of the draw tube for cleaning, inspection, maintenance, etc. necessarily requires complete disassembly of the device, thus causing down time for the machine tool.
In the prior art collet closers, the seals frequently fail, since they also provide the function of supporting the device.
Prior art collet closers also require the hydraulic fluid to circulate through the ball bearings, thereby increasing power use and tending to raise the temperature of the device.